1. Field of Invention
The present invention relates to a railway car coupler and more particularly to a shelved coupler having an anticreep protection means operable to prevent accidental unlocking of the coupler during movement of a railway car along a track.
2. Prior Art
Conventional AAR Standard railway couplers generally have an articulated rotary locklift assembly to operate the locking mechanism of the coupler resulting from a torque applied to it by an operating rod. The articulate and rotary arrangement of the locklift assembly permits longitudinal translation as a result of longitudinal buff and draft forces occurring during the normal operation of the railway car. The mass inertia of the locklift assembly about its point of suspension can result in a vertical force to activate and release the lock. The locklift assembly is constructed and arranged to prevent accidental unlocking of the knuckle due to such inertia buff forces. This is generally accomplished by the provision of an anticreep prong structure in the locklift assembly to engage with a front face ledge of the coupler head positioned in the vertical path of movement of the anticreep prong so that vertical motion of the locklift assembly transmitted from the longitudinal forces occurring during car operation is stopped by the front face ledge and prevented to activate and release the locking mechanism.
A Standard railway coupler may include a bottom shelf means having a horizontal shelf depending below the knuckle so that the underside of a mating coupler knuckle may engage with the shelf to limit relative vertical movement between a mating coupler. This bottom shelf means is generally formed on a wall depending downwardly from the underside of the front face of the coupler. A vertical portion of the wall may lie in the path of longitudinal movement of a locklift assembly laterally displaced due to a bent, worn or a damaged operating rod mechanism so that the anticreep prong fails to engage with the front face ledge. Failure to provide anticreep protection may result in the transmission of longitudinal inertia forces to vertical forces which activate and release the locking mechanism thereby causing inadvertent uncoupling.
Representative but non exhaustive of anticreep protection device relating to couplers are U.S. Pat. Nos. 3,114,461 and 3,572,518.